Aircraft structures often provide complex and costly challenges to both design and manufacturing. The underlying structures must not only meet strength requirements, but must also survive constant weight reduction requirements and manufacturing cost and time restraints. As such, a reanalysis and creative investigation into existing structures bears the possible reward of considerable benefits during implementation.
Such is the case with the fuselage section of the aircraft. Specifically the forward section commonly referred to as section 41. This fuselage section includes complex geometry and structure by way of the inclusion of both the nose section as well as the cockpit windows and similar features. Additionally, this portion of the aircraft comes under close scrutiny for its ability to have bird strike resistance. As such, section 41 barrel sections are often over designed which may lead to excess weight and more commonly excess cost.
Present fuselage sections are commonly are centered around designs that are stout and heavy. Often the outer skin and other structural supports are formed from aluminum which when overloaded may result in costly damage or repair. Bird strike incidents, even on designs that are not overloaded, may leave large dents in the aluminum structure that eventually require costly repairs. When overloaded, however, portions of the aluminum structure may rupture requiring extremely expensive repair or replacement. The aluminum skin also requires complex manufacturing and assembly as the skin is commonly backed by very heavy and complex beam structures. Structures such as stringers are required for support and add both considerable cost in addition to weight to the aircraft. The complex curvatures of the skins, especially in the nose region, often require manufacturing using expensive computer controlled machines. The quantity and complexity of manufacturing and assembling these aluminum structures often make section 41 the most expensive barrel section in the entire aircraft body.
What is needed is a design and method for manufacturing this complex section of the fuselage that allowed for simplification of manufacturing while simultaneously allowing for a compliant approach to bird strike resistance. Additionally, it would be highly desirable to have such a design and method that provided opportunities to reduce section weight in addition to manufacturing costs.